Improved valve-chest for steam-engines



UNITED STATES V PATENT CEEICE.

THOMAS S. DAVIS, OF JERSEY CITY, NEW JERSEY.

IMPROVED VALVE-CHEST FOR STEAM-ENGINES.

Specification forming part of Letters Patent No'. 39,125, dated July 7,1863.

To all whom it may concern:

Be it known that l', THOMAS S. DAvTs, of Jersey City, in the county ofHudson and State of N ew Jersey, havenventedanew and useful Improvementin the Valve-Chests of Steam-Engines; and I do hereby declare that thefollowing is a full, clear, and exact description ofthe same, referencebeing had to the accompanying drawings, forming part of thisspecification, in which- Figure l is a centrallongitudinalsection of avalve-chest constructed according to my invention. Fig. 2 is atransverse section of the same in the line x x of Fig. l. Fig. 3 is agansverse section of the same in the line 3/ y,

ig. l.

The main obstacle which has heretofore presented itself to thesuccessful use of piston valves for the induction and eduetion ofsteamengines has been the unequal expansion ofthe cylindrical bearingsor seats in which such valves work, which has caused the valves eitherto bind during a portion or portions of their stroke or else too t tooloosely durin g another portion or portions thereof, and I believe thatbut for this diiiculty such valves, owing to the simple manner in whichthey can be balanced,77 would have been more generally adopted.

The object of my invention is to provide for the equal expansion of thecylindrical bearing or seat throughout its lwhole length; and to thisend it consists in a certain arrangement of a steam-jacket surroundingor partly surrounding the whole length of the bearing or seat andcommunicating with both ends thereof in such manner that the steam willheat the said bearing or seat equally throughout its whole length.

To enable others skilled in the art to construct and apply my invention,I will proceed to describe it.

The valve-chest is composed of an outer casing, A, and an innercylinder, B, to which the two piston-valves C G are fitted, the saidcylinder being openat its ends and so arranged within and being so muchshorter t-han the said casing that the space a between them forms asteam-jacket, which not only nearly surrounds the sides of the cylinder,as shown in Fig. 3,

but is open to the ends thereof, as shown in Fig. 1.

The casing may be so constructed that the steam jacket or space a mayentirely surround the inner cylinder, except at the ports b b, throughwhich the steam enters and leaves the main cylinder of the engine.

The casing and cylinder may be composed of a single casting or be madeof two separate castings and the cylinder secured within the casing inany suitable manner.

The steam-chest thus constructed is secured to the main cylinder bybolts passing through flanges c c, or in any other suitable manner. Inthe ends ofthe casing there are provided openings opposite to andsomewhat larger than the bore of the cylinder B, for the introduction ofthe piston-valves C G', and these openings are tted with steam-tightbonnets D D', in which there are stuffing-boxes d d, through which worksthe rod E, to which both of the piston-valves are secured. The openin gj', to which the steam-pipe is connected, communicates with the space orjacket a at any part of its length, and the opening g, to which theexhaust-pipe is connected, communicates with the interior of thecylinder B, be,- -f

tween the piston-valves. Opposite the ports b b there are formed aroundthe interior of the cylinder B grooves e e', which correspond in widthwith the ports, and which are filled with steam from the ports so thatthe pistonvalves are balanced on all sides in passing the ports.

The operation is as follows: The steam, en-

tering the jacket or space a, envelops wholly,

or as far as permitted by the construction ot' the casing A, the wholelength of the cylinder B from end to end, and as the Valves respectivelymove inward from their respective ends of the said cylinder the steamenters the said cylinder from the ends and thence enters the ports b b',as they are uncovered by the valves, and as the valves move outwardtoward their respective ends ofthe cylinders and again uncover theports, the steam passes out from the main cylinder B, between theValves, and thence to the exhaustopeningg. It will thus be seen that theentire length of the cylinder B from end to end is heated by the steamand lts expansion from end to end is uniform, or sufficiently for allpractical purposes.

What I cla-im as my invention, and desire to secure by Letters Patent,is-

'lhe arrangement of the openended valvecylinder B, within the casing A,in such manner that a steam jacket or space, a, is, formed between them,Which surrounds or nearly surrounds the Whole length of the saidcylinder THOMAS s. nAVis.

fitnesses J. W. GooMBS, JONATHAN DAVIS.

